(a.) Nitric Acid, the only one of all the acids, that can be of any use to the anatomists, preserves well, it is true, the preparation of the nerves, hardening their structure, and increasing their nacreous white colour; but it deteriorates all the other structures, it dissolves the gelatine, softens the muscles, and deprives the bones of their calcareous salts; it cannot be other than deleterious to objects of pathological anatomy, and natural history.
(b.) Alcohol, is more serviceable than any other liquor in use, but its high price renders its employment almost impossible for objects of normal anatomy; it hardens and sensibly alters objects of pathological anatomy; and these alterations, however trifling they may be, and unimportant to regular anatomy, are serious for the physician, who cannot have too exact an idea of the progress of disorganization in the living tissues. If alcohol is eminently useful for natural history, its costliness renders it impossible to extend the use of it as far as the interest of science demands.
(c.) Diluted Alcohol, to which is added the deuto-chloride of mercury, is a less expensive liquor; it preserves accurately enough the labours of the naturalist and anatomist, but it is not sufficiently faithful for a pathological anatomy. The same may be said of the hydro-chlorate of soda, the hydro-chlorate of ammonia, the muriate and nitrate of alumine added to alcohol.
(d.) Alum, which we have seen figure in many of the adopted formulæ, is, nevertheless an unprofitable means of preservation. Extensively used in commerce, and employed from time immemorial in dyeing, it has only recently attracted the attention of preparers. This salt, to which the new chemical nomenclature has successively assigned the names of double sulphate, triple sulphate, acid sulphate of alumine and potash; has been experimented upon by myself, and has not answered my expectations. I have investigated the cause of this failure, and think I have found it; in analysing this compound, for every hundred parts I have obtained
| Sulphate of alumine, | 36 | .85 |
| Sulphate of potash, | 18 | .15 |
| Water, | 45 | |
| –— | ||
| 100 |
One hundred parts of this salt contains 10.86 of alumine. At the temperature of 12° centigrade, five hundred grammes of water dissolves thirty grammes of salt, from whence it results that a pound of water contains in solution only eighteen grains of alumine; from whence I have suspected that the little efficacy of alum for the preservation of animal matter, depends on the too small quantity of alumine in the solution. A fact convinced me that I was right: twenty-four hours after the immersion of a corpse in a bath containing the acid sulphate of alumine, I have observed that all the alumine was absorbed by the animal matter. Finally, the experiments which I have tried with the salts of alum, more rich in alumine, and more soluble in water, and the happy results I have attained, authorizes me to say: alum is a bad means of preservation, because it is not sufficiently soluble, and does not contain enough alumine. The reader will naturally again recur to the subject when we come to the exposition of my researches.
Sect. 3.—Means of preservation applied to each tissue.
In our first paragraph, we have passed in review the different preparations which ought to precede the application of preservative means; in the second, we have seen these numerous means, and we were compelled to deliver an impartial judgment. It remains for us to explain here how anatomists have applied them to the tissues taken separately. We shall abstain from relating the preparations which precede the application of preservative means, because they are foreign to the subject which occupies us, and would uselessly prolong a discussion already too much extended.
1. Fibrous tissues.—Articulations, aponeuroses, tendons, and ligaments.—The process generally adopted is due to M. J. Cloquet, in nearly following the method employed by the tanner, he has succeeded in preserving the suppleness of these tissues.